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Hemerocallis

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last updated Mar 26, 2014
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Hemerocallis 'Cartwheels'

Hemerocallis (daylilies) produce elegant, usually trumpet-like blooms in summer and are easy to grow in many gardens. Individual flowers are short-lived but each plant produces many flowers, so displays will last for weeks.

Cultivation notes Back to top

Daylilies thrive in well-drained, fertile soil, but tolerate poorer soils and heavy clay. Avoid planting in heavy shade and borders that dry out in summer.

Planting and care

Before planting container-grown daylilies, improve the soil structure and moisture-retention by digging in well-rotted organic matter, such as garden compost or manure. The same materials can also be used as a mulch around existing plants in spring to help conserve moisture.

Where growth is unsatisfactory, apply a general-purpose fertiliser, such as Growmore, in spring at 50-70g per square metre (1½-2oz per square yard).

Daylilies bought in packets

Bare-root daylilies are often sold in packets at garden centres. These can produce good plants, but need more care initially. Check the plants in the packet are firm and you can see buds or small shoots. Avoid those with long pale shoots.

Pot them up, rather than planting directly in the ground, using a peat-free multi-purpose compost and water well. Place pots in a cold frame or cold greenhouse and keep the compost moist.

Once they are growing strongly, plant out, ideally, in spring or autumn.

Pruning and training Back to top

Daylilies do not require training or staking and there is no particular need to deadhead after flowering, but this will improve their appearance, and can help reduce infestations of hemerocallis gall midge (see problems below).

Propagation Back to top

Large clumps can be divided in spring or autumn, replanting 10-15cm (4-6in) wide sections 30cm (1ft) apart.

Cultivar Selection Back to top

For a list of reliable daylily cultivars to choose from, see the RHS Plant Selector.

Links

AGM plants
RHS Plant Finder

Hemerocallis 'Cartwheels'

Hemerocallis 'Cartwheels'

Problems Back to top

The main pest of daylilies is hemerocallis gall midge. The larvae develop in the buds, causing the flowers to distort or fail to open. Other pests that may be encountered include aphids, slugs and snails.

There are no significant disease problems. However, a new rust disease was found on an imported hemerocallis in 2001. Thankfully, it has not been reported in the UK since but remains notifiable. The typical symptoms are numerous yellow or orange pustules, mainly on the lower leaf surface but occasionally on the upper surface or stem.

Quick facts

Common name Daylily
Botanical name Hemerocallis
Group Perennial
Flowering time Early to late summer (late May to August)
Planting time Spring or autumn (April, late September and October)
Height and spread Up to 1.5m (5ft) by 90cm (3ft)
Aspect Sun or partial shade
Hardiness Fully hardy
Difficulty Easy
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